Bed plate for a card feed



July 4; 1961 w. J. WHEELER ETAL 2,991,075

- BED PLATE FOR A CARD FEED Filed Dec. 30, 1958 4 Sheets-Sheet 1 END END i G v INVENTORS.

WENDELL .1 WHEELER GORDON R. MORRIS BY PW M ATTORNEY July 4, 1961 w. J. WHEELER ET AL 2,991,075

BED PLATE FOR A CARD FEED Filed Dec. 30, 1958 4 Sheets-Sheet 2 y 4, 1961 w. J. WHEELER ETAL 2,991,075

BED PLATE FOR A CARD FEED 4 Sheets-Sheet 5 Filed Dec. 30, 1958 July 4, 1961 w. J. WHEELER ET AL E 2,991,075

BED PLATE FOR A CARD FEED Filed Dec. 30, 1958 4 Sheets-Sheet 4 I a A.

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United States Patent 2,991,075 BED PLATE 'FOR A CARD FEED Wendell J. Wheeler, Endwell, and Gordon R. Morris,

Owego, N.Y., assiguors to International Business Machines Corporation, New York, N.Y., a corporation of, New York Filed Dec. 30, 1958, Ser. No. 783,922 7 Claims. (Cl. 271-41) This invention relates to high speed'card feeding systems for business machines, and, in particular, to an improved bed plate for feeding flat or warped cards at high or low speeds in sorting, collating, punching or other like business machines.

In prior art card feeding machines, cards are stacked in a container known as a hopper and are permitted to settle on a picker knife and throating device. The picker knife singly removes the cards from the hopper. A bed plate positioned between the picker knife and throating device assists in supporting the cards in the hopper. The cards then singly pass through the throating device into a set of feed nolls into the card transport section. Additional feed rolls then transport the card throughout the machine where various operations are performed. These operations may be in the nature of sorting, collating or punch ing, etc.

In most card feeding mechanisms, the cards settle on the picker knife and throat block and are generally supported thereby. Since the cards are more frequently found to be in a warped condition rather than in a fiat condition, the bed plate is lowered below the card feed line by an amount equal to the maximum degree of warp that exists in a card when a card is positioned in the hopper. The clearance of the bed plate below the card feed line is found necessary to allow the card to lay down on the picker knife and throat when it was warped.

There are several types of wanp. The cards can have a top-to-bottom warp with the center portion of the card convex and the portion of the card at the throat gap and picking surface of the picker knife curved down. When in this condition, the trailing edge of the card can be engaged by the picker knife surface and the leading edge of the card can be positioned in the throat gap. Another type of warp is top-to-bottom warp with the leading and trailing portions curved up. In this type of warp, the trailing edge of the card may not be engaged by the picker knife and on occasion may not pass into the throat gap. Another type of warp is commonly referred to as end-toend wanp with the side portions of the card bent down and the middle portion convex. This condition would normally cause the center portion of the card to extend above the picker knife and throat if the bed plate were not dropped below the card feed line. Another condition of card warp is endto-end card warp with the edges of the card warped up. A large degree of this type of warp can be acceptable since the picker knife can still engage the edge of the card to move it into the throat. Still another type of card warp is commonly referred to as diagonal warp which can be a combination of several of the four types of warp mentioned above. Furthermore, it is quite common for the position of the maximum warp in a card to be closer to one edge than another and generally it is not at the center of the card itself. Therefore, in order to accommodate these different types of warps in a card, it has been the practice to provide a flat bed plate which is located sufiiciently below the card feed line so that if any of the warps mentioned are present they will not force the cards to extend above the critical picker knife and throat block areas.

The dimension, for locating the bed plate below the card feed line, is obtained from the specifications preice scribed by the manufacturer for maximum acceptable card warp. A standard that has been used requires that the card not have any greater than a one-eighth inch /8") top-to-bottom warp, one-quarter inch (MW) endto -end warp and one-quarter inch 0A) diagonal warp. Now, the bed plate is positioned below the card feed line so as to accommodate the warped cards. This permits the marginal edges, with the card at /8" top-tobottom warp, to settle at the critical picker knife and throat areas while pressure acts on the cards. The pressure on the deck of cards, in addition to the A3 bed plate clearance, usually is sufiicient to accommodate the greater end-to-end and diagonal warp.

This invention is particularly concerned with the arc picker type of feed system. In this system, the cards are picked singly from the hopper by a picker knife which is reciprocated or oscillated about a fixed pivot. As this are type of picker knife moves forward, the base of the picking knife surface moves in the path of an arc. Therefore, just prior to the picker knife moving forward, it is positioned above the card feed line at the instant that the card is engaged by the picker knife. For purposes of this invention, the card feed line is intended to cover that line from the throat to the card picking surface when the picker knife is at rest in its rearward position. With the continued forward movement, the base of the picking surface drops below the card line as the card is moved into the feed rolls. The cards in the hopper drop with the picker knife. However, when the picker knife returns to pick the next card on its return stroke, it tends to bounce the deck upwardly in the hopper. Therefore, the cards are continually moving up and down with the motion of the picker knife. This is commonly called deck disturbance. Deck disturbance can also occur with slideable picker knives since the warp in the cards can also cause the deck to move up and down.

Now, in low speed feeding machines, the movement of the deck does not create a critical problem since the cards have a sufficient amount of time to settle before the next card is picked. However, when operating at high speeds the cards are jarred more strenuously by the picker knife during its return stroke so that the cards frequently do not have the time to settle in the hopper and be in position when the picker knife moves forward. It would be accidental if the bouncing were in timed relation with the motion of the picker knife. In some existing machines, this accounts for the picker knives failing to provide good engagement of the picker knife with the card during high speeds. The card is either missed by the picker knife or is nicked by the picker knife so as to be damaged. Also, the card does not align properly at the throat gap.

Attempts have been made to provide various types of contoured bed plates to accommodate warpage in feeding cards, sheets or the like. In most of these prior art devices, the bed plate is concave with the front edge leading gradually upward toward the throat. The purpose generally being to gradually guide a card, whose front edge is bent downward, into the throat. Generally, the bed plate is concaved arcuately toward the throat. In these configurations it is intended that the leading edge of the card scrub the arcuate portion of the contoured plate as it is being moved forward by the picker knife. Furthermore, the card is supported at other than the picker knife and throat areas. Therefore, when operating at high speed the leading edge of the card extends above the throat and becomes mutilated.

Other prior arrangements provide convex type bed plates which are convex in both directions. Such an arrangement does not recognize the worst conditions of card warp in card feeding arrangements so that if the top-to-bottom warp, with the edges curved upward, were encountered, the convex formation would push the edges above the picker knife and throat gap so that the card would be caused to jam the feed system.

For these and other reasons, the prior bed plate configurations have not provided the proper contour to the bed plate to accommodate those warps which cause the greatest amount of card damage in a card feed system.

It is therefore an object of this invention to provide an arrangement for card feed systems utilizing an arc picker type picker knife, which arrangement minimizes the amount of difference in elevation between the level of the bed plate and the level of the picking Surface and is capable of substantially eliminating card disturbance in the hopper.

It is another object of this invention to provide a contoured type bed plate which can accommodate those cards having top-to-bottom warp with the edges curved upward and end-to-end warp with the edges curved downward to thereby substantially eliminate card damage caused by the worst conditions of warp.

It is still another object of this invention to provide a contoured bed plate for a card feed system, which contour substantially supports the card at the picker knife and throat areas even though the card has a maximum acceptable card warp.

Briefly stated and in accordance with one aspect of this invention, we substantially eliminate card disturbance by providing a contoured bed plate which is concave in one direction and convex in the other transverse direction, with the arc picker type of picker knife being positioned so that the path of the picker knife substantially defines the angle that the bed plate makes with the card feed line, which angle is the chord of an are made by the picker knife in passing from its at rest position behind the card deck to the position corresponding to the entry of the card into the first feed rolls. We further contour the bed plate to have its maximum deviation in elevation from the level of the card feed line at its center, with the leading portion of the bed plate being at an angle to the card feed line so that the leading portion of the card is substantially parallel to that surface of the bed plate without extending above the throat, and we further provide intermediate curved portions having changing centers of radius of curvature, and the point of maximum deviation of elevation from the card feed line (maximum acceptable card warp) at the center of the bed plate.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of examples, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

FIG. 1 shows a schematic view of a sorter.

FIGS. 25 show the most frequent types of warp.

FIG. 6 is a view in perspective showing the bed plate in its environment.

FIG. 7 is a cross-sectional view taken on lines 77 of FIG. 6.

FIG. 8 is a cross-sectional view taken on lines 8-8 of FIG. 6.

FIG. 9 is an enlarged view showing the path of the picker knife with respect to the bed plate.

FIG. 10 is an enlarged view of the bed plate.

Referring to FIG. 1, a schematic view of a sorter is generally shown at 10. Although this invention is described in connection with a sorter, it is understood that the invention is applicable to other types of business machines such as collators, punches, etc. A hopper is shown at 12 which contains a deck of cards 14 which are adapted to be singly removed from the hopper by a picker knife 16 and passed over a throat block 17 which defines a throat with the front wall of the hopper. Feed rolls are shown at 18 through which the cards are fed. Sensing means 20 is provided for sensing the card so as to operate the appropriate magnet 22, and in turn chute blades 24 to deflect the cards through the appropriate additional feed rolls 26 into the proper pocket 28. In this manner, cards may be sorted according to the information read from the sensing means 20 which are connected by a suitable electrical system for operating the proper magnet and chute blade to deflect the card into its appropriate pocket 28.

Generally the cards that are continually used in business machines do not lay flat. If the bed plate is flat and lies on the card feed line extending between the picker knife and the throat, then if a warp appears in the card, a critical portion of the card may extend above the picker knife or the throat or both. When this occurs, either the picker knife surface will not engage the edge of the card to push it through the throat, or, the leading edge of the card will protrude up above the throat gap so as to not pass through the throat. Either of these conditions will cause feeding failure. Therefore, the fiat bed plate is positioned below the card feed line to accommodate the warp.

Reference is now made to FIGS. 2-5 where the picker knife 16 is shown provided with a picking surface 30, adapted to engage the trailing edge 32 of the cards 14. A bed plate is shown at 34 extending from adjacent the picker knife to a throat gap defined by the knife edge 36 of the hopper and the throat block 17 mounted in the bed plate 34. This bed plate is shown in flat condition in FIGS. 2-5 and dropped /8" below the card feed line to explain the problem confronting the prior art.

In general there are four basic types of warp. FIG. 2 shows an end-to-end warp with the marginal portions of the card warped down. FIG. 3 shows another endto-end card warp with the marginal portions warped upwardly. FIG. 4 shows a top-to-bottom warp with the ends warped downward. FIG. 5 shows a top-to-bottom warp with the ends warped upwardly.

Referring to FIG. 2, it will be noted the warp tends to extend above the picker knives 16, whereas the warp in FIG. 3 is still capable of being engaged by the picker knives. Therefore, the condition of FIG. 2 is the worst condition of these two. Comparing FIGS. 4 and 5, it is noted that the warp in FIG. 4 still has a tendency to be engaged by the picker knives, whereas, the warp in FIG. 5 results in a tendency for the marginal edge of the card to extend above the picker knives 16. Therefore, the worst condition of this type of warp is that of FIG. 5.

In order to take care of the two worst conditions of warp, namely, that of FIG. 2 and that of FIG. 5, the prior systems used a flat bed plate which was positioned below the card feed line by an amount (hereinafter referred to as clearance) equal to the maximum allowable warp of the card. Therefore, as the picker knife progressed forward to deliver a card through the throat, the clearanc-ewas suflicient to accommodate the warp. However, with an arc type picker, the picking knife surface drops below the card feed line thereby dropping the complete stack. Since the cards are supported at the throat and at the picker knife, the deck is disturbed by moving downwardly with every forward stroke of the picker knife and then upwardly with the return stroke of the picker knife. In low speed card feed machines, the arc type of picker knife does not produce significant adverse effects with respect to the balance or joggling of the deck to cause an unacceptable amount of card damage. However, when operating at higher speeds, the picker knife jars the cards to such an extent that the cards do not have an opportunity to resettle back on the picker knife at the time the picker knife is ready to deliver the next card. In other words, the bouncing is not in timed relation with the oscillations of the picker knife. Further, even with picker knives that reciprocate in a straight line path, the warp in the card being picked causes the deck to bounce.

Reference is now made to FIG. 6 where the hopper 12 is shown in greater detail and is constructed in the same manner as other hoppers. The hopper contains a front wall 40, hopper side walls 42 (only one shown), and hopper posts 44 (only one of which is shown in its proper position for purposes of clarity). These define the hopper and are slightly larger than the cards so that' they can be joggled by appropriate joggling means (not shown) to provide smooth card settling. Cutout portions 46 are provided in the hopper front wall to pro vide clearance for card guide rolls 47 and for the first feed rolls 18. A throat knife blade 48 is shown fixed to the front wall and terminates into a knife edge 49. The front wall of the hopper is bent so as to form the upper portion 50 for a throat chute which provides guidance for the card in the card transport section.

In order to help support the deck of cards, a bed plate 52 is provided. The bed plate is contoured to have a concave shape in the direction shown at 54 and a convex shape in the direction shown at 56.

A throat block 17 provided with a tip 57 is shown mounted in the bed plate and follows the contour so as to merge to the same level with the bed plate to combine with the knife edge 49 of knife 48 to form a throat gap 58 (see FIG. 7). The throat block contains slots 60 and passageway 61 through which vacuum can be applied to the cards at the throat gap 58.

In order to remove the bottom-most card from the deck of cards in the hopper, the picker knife is oscillated to and fro in cutout portions 62 in the bed plate. Vacuum slots 64 are provided in order to pull the card down onto the picker knife. Details of the vacuum control system form no part of this invention and therefore will not here be described in detail, especially since they are fully disclosed in the prior art.

Although this invention is described in connection with a vacuum system as the preferred embodiment, it can be used with other types of card feed systems which have are type pickers or straight line path type pickers.

Illl has been found that the bed plate must contain a particular type of contour in order to insure that the cards will settle at the picker knife and throat to provide satisfactory feeding of cards at high speeds. Therefore, the contour of the bed plate will now be described.

As noted above, in order to overcome the deck disturbance and to more effectively accommodate warped cards at high speeds, the bed plate is concave in the toptb0ttom warp direction as shown by the arrows 54 and convex in the end-to-end warp direction as shown by the arrows 56. FIG. 9 shows the angle of the bed plate coinciding with the chord of the arc of the picker knife to minimize deck disturbance. Therefore, the picker knife extends only a sufficient distance above the bed plate to engage the card and maintains this engagement over the distance that it takes to pass the leading edge of the card through the throat gap 58 into the first feed rolls 18. The amount that the base of the picking knife surface 30 moves above and below the bed plate is decreased to such an extent that deck disturbance is substantially eliminated.

The bed plate is shown in FIGS. 6-10 and particularly FIG. 9 where two conditions are met at the picker knife. First of all the bed plate is made to conform to the arc of the picker knife arm 16. It is known to make the picker knife arm sufiiciently long so that the base of picking knife surface 30 stays in engagement with the card from its fully restored position over that distance that it takes for the picker knife to push the leading edge of the card into the feed rolls 18. The length of the picker knife arm 16 establishes the length of the radius of curvature 61 to the base of the picking knife surface at 30. The point 30 makes an are 62 and chord 63 which is at an angle 64 with the card feed line 70. The bed plate is dropped a sufficient amount to insure engagement of the card by the picker knife. With the assist of vacuum applied to the picker knives, .010 was found sufiicient. The trailing portion 65 of the bed plate 52 is defined by the angle of the chord 63 and the amount the bed plate is dropped below the chord 63. This de fines the trailing portion of the bed plate as best seen in FIG. 10.

The bed plate, as viewed in FIG. 10, is at its maximum distance 74 below the card feed line 7 0 at the center portion. This is referred to as a clearance and is established by the amount of acceptable card warp set by the card manufacturer. This is generally /8 (.125") for topto-bottom warp. The bed plate is therefore contoured to a depth of /8 below the card feed line at the center as shown at 74.

Since the point of maximum top-to-bottom warp of a card may drift about the center line of the card, the central portion of the bed plate is contoured to accommodate this variation in card warp within ten percent of card length. This is the maximum deviation of acceptable drift of warp established by card manufacturers. Since the card length is 3%", the maximum acceptable drift of warp is approximately .325, or about .1625" on each side of the card centerline. Therefore, the bed plate is made flat to each side of the center of the bed plate by this amount as shown at points 76 and 78. This flat portion at 76, 78 is maintained at the maximum distance 74 below the card feed line 78.

In order that the bed plate be capable of accommodating cards delivered at high speeds having maximum warp, or no warp at all, the leading portion 71 of the plate is contoured to make an angle 72 (FIG. 10*) to the card feed line 7 0 rather than have an arc form. This angle must be such that the leading edge of the card is sup ported only at the throat even though it has maximum card warp. If the contour were such that it would be supported at some other intermediate point, the leading edge of the card would tend to extend above the throat and result in a jam. Also, if the angle were too small, the card would be supported at an intermediate portion of the bed plate and force the leading edge of the card above the throat. The maximum limit of the angle is established at that angle where the card will not buckle and thereby force the leading edge of the card above the throat. The buckle, if any, will take place at a point between the center of the bed plate and the throat. Therefore, with the proper angle, the card will not be able to buckle more than the standard maximum allowable card warp and the leading edge will not extend above the throat. Therefore, the angle 72 of the bed plate is established at a minimum and maximum angle so that the leading portion of the card will not extend above the throat. In has been found that with a /s (.125 clearance, a minimum angle of 6 on the throat block and bed plate is required to obtain satisfactory card delivery at high speeds, which angle also satisfies the buckling problem.

As pointed out above, the length of the trailing portion 65 of the bed plate is determined by the distance that the picker knife stays in engagement with the card. The length of the leading portion 71 is determined by drawing a line parallel to the card feed line 70, from the terminating point 73 of the trailing portion, so as to intersect one arm of the angle 72 at 75.

Another important aspect of this invention is the manner in which the contour of the bed plate is blended between the points at 76 and 78 and points 73 and 75 at the angular end portions at 64 and 72. The intermediate portion 80 between points 73 and 76 has a contour defined by a fixed radius of curvature 82. The center 84 of this radius of curvature is determined by bisecting the distance between points 73 and 76 and constructing a line normal to this distance. The center of radius of curvature 84 is established at that point where the arc at 8-6 is substantially tangent to the trailing portion 65 at point 73 and substantially tangent to the fiat portion at point 76. The intermediate portion at 88 between points 75 and 78 has a contour defined by a fixed radius of curvature 90. The center 92 of this radius of curvature is established in the same manner as center 84. Since the angle at 64 will generally be different from that at 72, the length of the leading portion at 71 will be different from the trailing portion 65. Therefore, the radius of curvature will generally be different although it is possible for them to be similar. It has been found that an are passing through points 30 and 57 and passing through the point of maximum clearance at the center at 74 is not satisfactory for high speed card delivery. Therefore, the intermediate portions of the bed plate 52 are contoured according to changing centers 84 and 92 of radius of curvature 82 and 0 which is blended into the end portions 65, 71 and to the flat center portion at 76, 78. The curvature is such that an intermediate portion of the card having maximum warp is not supported on the intermediate portion of the bed plate.

In order to accommodate the worst condition of card warp in the end-to-end direction, the bed plate is chamfered a shown at 76 in FIG. 8. This chamfer assists in avoiding jams where the card enters the feed rolls. If the bed plate were flat, or only contoured in the direction shown by the arrows 54, FIG. 6, then if the card had an end-to-end warp with the ends warped down, a portion of the leading edge of the card would tend to be above the tangent point of the feed rolls 18 (see FIG. 2). The chamfer permits the outer ends to drop so that the inward portions of the leading edge of the card aligns with the tangency point on the feed rolls and provides a three point support at the throat block and two picker knives. The chamfer is made to accommodate the maximum acceptable card warp in this direction. Therefore, when the card has an end-to-end warp with the ends warped down, the leading and trailing edges of the card will settle properly at the picker knife and throat.

The contour of the bed plate is, therefore, defined by the angle of the chord of the picker knife arc, the throat angle, the maximum distance below the card feed line at the center portion, the intermediate portions having a curve with different centers of radius of curvature, and the chamfer angle in the end-to-end warp condition.

It is noted that the 6 throat angle and the angle 64 at the picker knife must be such as to stay below an imaginary are passing through the point 57 on the throat block at the throat gap, the point 30 at the base of the picking knife surface in its restored position, and through the point of maximum clearance of card warp at 74. If an arc were used for the bed plate contour, the leading edge of the card would tend to position itself above the throat since some portion of the card remote from the leading edge will be supported on the arc contour.

It is important that the angle on the throat be a mini mum amount for a maximum acceptable warp. The angle should be such as not to support any portion of the card but just barely the front of the card. If the angle is too small the bed plate will support the card back from the leading portion of the bed plate. This condition will position the leading edge of the card above the throat gap 58.

In operation, the base of the picking knife surface will follow the contour of the bed plate so that the cards in the hopper will not be bounced upwardly on the return stroke of the picker knife. The cards will merely have a tendency to melt away as they are picked by the picker knife. Furthermore, if the card has a top-to-bottom warp of a maximum of .125, it still will be satisfactorily handled by the throat and picker knife. The contour of the bed plate will prevent the picker knife from buckling the card beyond the .125" maximum. The bed plate prevents the buckling of the card which would cause improper timing and result in poor machine operation. Since the angles on the bed plate are generally greater than and lay below the theoretiqal are conmeeting the tip 57 of the throat block and the point 30 at the picking knife surface, the card will be supported only at the throat and picker knife so that the leading edge of the card will not be lifted above the throat.

The contoured bed plate is particularly advantageous with the vacuum type feed system with the vacuum ports effectiveness of the vacuum in holding the card down on the picker knife during its forward stroke.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a card feed mechanism comprising a hopper containing a deck of cards, feed rolls for receiving cards from the hopper, card picker means for singly removing the cards from the hopper to deliver them into the feed rolls, the level of the card picker means and card feed rolls defining a card feed line, a bed plate positioned adjacent the card picking means, the card picking means extending above the bed plate and traversing in an arc, the bed plate containing a contour over the length of the path of the picker knife while it is in engagement with the card, said contour being at an angle to the card feed line which substantially follows the chord of the are made by the picker knife, and said contour being generally convex in a direction transverse of the card feed line, thereby to substantially eliminate misfeeding despite a card being warped end-to-end or top-to-bottom.

2. A concave-convex contoured bed plate for use with an arc picker in a card feed mechanism, the leading and trailing edges of the bed plate being on the card feed line and the intermediate portion being below the card feed line with the side portions being chamfered so that their edges are below the card feed line, the concave portion having a contoured trailing edge which is at an angle parallel to the chord of the are transcribed by the are picker.

3. A concave-convex bed plate for use with an arc type picker knife in a card feed mechanism adapted to accommodate warped cards having a top-to-bottom warp with the leading and trailing edges curved up and an end-to-end warp with the side edges curved down, the bed plate being concave from the picker knife portion to the throat portion and the bed plate being convex from one edge to the other edge.

4. A concave-convex bed plate for use with a picker knife in a card feed mech nism. the path f he picker knife being in an arc, the leading and trailing portions of the bed plate being on the card feed line, the bed plate having a concave contour with the portion at the trailing edge having an angle which substantially coincides with the chord of an are formed by the picker knife While it engages the card, a center portion being below the card line by an amount equal to the maximum allowable Warpage of the cards, a leading portion having an angle such as to support the card at the leading portion and intermediate portions having a curve with a changing center of radius of curvature.

5. In combination, a concave bed plate for use in a card feed system and adapted to accommodate cards up to la" top-to-bottom warp, a hopper for the cards, a picker knife for removing the cards from the hopper, a card feed path, the picker knife having a picking surface which traverses in an arcuate path, the bed plate having a leading portion which is at a minimum angle of 6", a trailing portion which is at an angle equal to the chord of the are made by the picker knife, a center portion, and intermediate portions connecting the two leading and trailing portions with the center portion having separate changing centers of radius of curvature.

6. The combination as in claim 5 wherein the center portions of the bed plate are /6 below the level of the card feed path.

7. In a card feed system, a hopper, picker knife and throat, the level of the picker knife and throat defining the card feed line, a bed plate having a contour for accommodating cards having top-to-bottom warp with the ends warped up, the angle of the trailing portion of the bed plate being substantially parallel to the path of the picker knife, the leading portion of the bed plate being substantially equal to the angle of the leading portion of the card so that the leading edge does not project above the throat even though the card has maximum acceptable card warp, a center portion which is below the level of the card feed line by a distance substantially equal to the maximum acceptable card warp, the center portion being flat over a distance substantially equal to the maximum acceptable drift of the card warp, and intermediate portions having different centers of radius of curvature, so that a warped card will not extend above the picker knife and throat even though it has top-tobottom warp.

References Cited in the file of this patent UNITED STATES PATENTS 192,519 Leavi-tt June 26, 1877 1,147,482 Cheshire July 20, 1915 1,763,039 Ford June 10, 1930 2,158,505 Horgan May 16, 1939 2,877,017 Luning et a1 Mar, 10, 1959 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,991,015 July 4 1 51 Wendell .I, Wheeler et a1,

It is hereby certified that error eppears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below v Column 8. line 72, for "to 1/6" top-to-hottom" read to 1/8" top-to-bottom column 9, line 8, for "are 1/6" below" read are 1/8" below Signed and sealed this 3rd day of April 1962.,

(SEAL) Attest:

ERNEST W. SWIDER 7 DAVID L. LADD Attesting Officer Commissioner of Patent 

